Trimming and material folding device for overlock sewing machine



June 28, 1966 R. H. MICHAUD 3,257,979

TRIMMING AND MATERIAL FOLDING DEVICE FOR OVERLOCK SEWING MACHINE Filed May 5, 1964 5 Sheets-Sheet l June 28, 1966 R. H. MICHAUD TRIMMING AND MATERIAL FOLDING DEVICE FOR OVERLOCK SEWING MACHINE 5 Sheets-Sheet 2 Filed May 5, 1964 June 28, 1966 H, MICHAUD 3,257,979

TRIMMING AND MATERIAL FOLDING DEVICE FOR OVERLOGK SEWING MACHINE Filed May 5, 1964 3 Sheets-Sheet 3 United States Patent ice This invention relates to an improved apparatus for obtaining a stronger seam made on a Superlock Sewing Machine, manufactured by Willcox and Gibbs Co. The

object of this invention is to enable more material to be held from the stitching point of the needle to the edge of the material after the blades have trimmed the material. A further object is to make a narrower appearing seam and still have the desired width of material sewn into the seam.

A further object of this invention is to operate on machines that have a shirring attachment and still produce a stronger seam, while allowing shirring to be performed.

A further object, and one of primary importance, is to produce strong seams that resist tearing under strain. Flannel and other materials that tend to unravel readily when sewn near the edge, come apart easily under tension, but are held more successfully together when joined by seams made with this device as compared to ordinary flat overlock seams.

Referring to the drawings,

FIGURE 1 is a perspective view of apparatus embodying the invention;

FIGURE 2 is an exploded perspective view, on a larger scale, of the presser foot and folder assembly;

FIGURE 3 is a perspective view of the throat plate;

FIGURE 4 is a perspective view of a spacer to elevate the throat plate;

FIGURES 5, 6 and 7 are perspective views, respectively, of the upper blade clamping shoe, the upper blade and the lower blade;

FIGURES 8, 9 and 10 are plan, front elevational and side elevational views, respectively, of the folder; and

FIGURE 11 is a plan view of a piece of fabric showing the successive operations performed thereon bythe mechanism illustrated in FIGURE 1.

The improved mechanism is shown in FIGURE 1 in connection with parts of a standard Willcox and Gibbs Superlock Sewing Machine. A portion of the machine frame 20 is shown on which a modified throat plate 22 is mounted with a spacer 24 beneath it to elevate it slight- 1y for a purpose hereinafter explained. Since the fabric to be stitched slides over the top surface of the frame member 20 and over the throat plate 22, the forward portion of the latter is preferably beveled as at 26 (FIG- URE 3) so as not to present an obstruction to the fabric. An end portion of the spacer 24 which projects beyond the side edge of the throat plate 22 has a raised portion 25 the top of which is flush with the top surface of the throat plate so that it acts as a lateral extension of the throat plate to prevent the fabric from slipping down between the throat plate and cutter blades.

A modified presser foot 30 is attached to the usual foot carrier 32, and a folder 34 is adjustably secured to the foot by a screw 36. This screw passes through a slot 37 in an extension 38 of the folder which fits in'a transverse channel 39 in the foot.

Patented June 28, 1966 The right hand edge of the throat plate 22 is reversely curved as at 40 and merges with a side of a narrow stitching tongue 42 integral-with the plate. This portion 40 of the edge of the plate permits the margin of the fabric on the plate to be folded or curled under around the stitching tongue 42 by the folder 34. When the two loopers (not shown) pass threads around the stitching tongue 42 in making overlock stitches, these threads also embrace the margin of the .fabric which is downwardly curled about the tongue. If the fabric is being joined to another piece of fabric superposed thereon, the margins of the two pieces are together curled about the stitching tongue 42 so that the stitches anchoring the overlock threads penetrate the pieces of fabric along a line well removed from the edge of the fabric pieces, and thus provide a strong seam joining the fabric pieces. The throat plate 22 is elevated by the spacer 24 so that the looper which operates below the stitching tongue will not engage the margin of the fabric which iscurled down around the tongue.

The shape of the folder 34 is shown in FIGURES 8, 9 and 10, the active part of the folder being a downwardly projecting horn or scroll 44 with a concave guiding surface 46 which contracts from front to rear with a decreasing radius of curvature to cause progressive curling of the margin of the fabric as it approaches and passes the stitching tongue 42.

To ensure a uniform overlock seam, the edge ofthe fabric passing over the throat plate is trimmed by shares consisting of a fixed lower blade 50 secured to a carrier 52 which is spring-pressed toward the right, as it appears in FIGURE 1, so as to press the blade against an upper blade 54 secured to a carrier arm 56 by which it is vertically reciprocated. The carrier arm is fixed on a short shaft 58 by which it is connected to a rod 60 of an eccentric (not shown) which rocks the carrier in the usual v and 55, respectively, so that the usual means for SCOUT-I ing the blades can be used without alteration.

The effect of the trimming, curling and stitching operations on a piece of fabric is illustrated in FIGURE 11. As the fabric advances the shears trim off a portion 72 of the margin to form a uniformly clean straight edge 74. The folder 34 causes this new edge to curl down and about.

the reversely curved edge of the throat plate and about the stitching tongue as at 76 so that the needle and loopers form the overlock stitches 78 about a doubled margin,

this operation taking place for one, two or more layers of fabric fed over the top surface of the frame 20. t

I claim:

In an overlock sewing machine, a frame, a throat plate on 'said frame having a stitching tongue integral therewith, a straight side edge and a downwardly convexly curved tapered transition edge portion extending between said side edge and said stitching tongue and merging with the outer edge of said tongue, means adjacent to said tongue for folding the margin of a fabric advancing over said throat plate down against said transition edge portion of the plate and then under said tongue in position to be embraced by the formation of overlock stitches about said tongue, 21 fixed lower cutting blade located adjacent to said straight side edge of said throat plate and spaced forwardly of said downwardly curved edge portion, an upper movable cutter blade cooperating with said fixed lower cutter blade, a spacer member between the bottom of said throat plate and said frame supporting said plate above its normal level, and guide means on said spacer member serving as an extension of said throat plate to guide said fabric and prevent the fabric, from falling between said throat plate and-said lower cutter blade.

References Cited by the Examiner UNITED STATES PATENTS Merrow l12151 X Heap 112162 Maier 112-260 Washburn 112126 Knaus -e 112122 Washburn 112260 JORDAN FRANKLIN, Primary Examiner.

R. J. SCANLAN, Assistant Examiner. 

